Dean R. Koontz wrote a novelization of the screenplay under the pseudonym Owen West. The book contains a lot of backstory added by Koontz. Because of this, and the fact that the book was released before the movie due to a delay in post production, it is often mistaken that the movie is based on the book, but the book is in fact based on the movie.

An accident occurred during filming when a carnival ride carrying several passengers was left on for about twenty minutes to half an hour. The ride, one which has several octopus arms that spin around with rotating carriages, normally only runs for about four minutes per joyride. Thrillseekers vomited and yelled out real screams as the ride continued way past its end time. When stopped, the riders could not walk and were somewhat twisted in their musculature. An ambulance was called but no one was seriously injured.

Some of the props in Joey's bedroom were owned by Shari Lewis of "Lamb Chop" fame (such as the winking ventriloquist dummy) and were obtainable because co-executive producer Mace Neufeld was a friend of hers.

The industrial crane used for crane shots on this movie could elevate higher than the ferris-wheel seen in the amusement park. The crane was gigantic. It had three sections which could each extend fifty feet. The film's D.O.P. wanted to have one on every movie he worked on.

Reshoots of scenes took four days due to lost film footage which had got caught up in a local teamster war. Director Tobe Hooper has said that the filming of this movie in Miami / Florida occurred during the Scarface (1983) era.

In a interview on the DVD, director Tobe Hooper said that the mask worn by one of the creatures in The Funhouse (1981) was a Frankenstein mask. Hooper said that this was selected because the Universal Studios owned the image copyright for it from their Frankenstein (1931) horror film classic.

The monster was played by Wayne Doba, a professional tap dancer and former mime making his film debut. His only other major film role for many years was Octavio the Clown in Scarface (1983), also shot in the Miami area.